Q14 - Archaeologist: An ancient stone

[ohthatpatrick]

Question Type:
Strengthen

Stimulus Breakdown:
Conclusion: This building was probably not a dwelling.
Evidence: This building is a mix of three types of stones. Most buildings from this time/place only had ONE type of stone, and most were human dwellings.

Answer Anticipation:
To prove that "X is probably Y", you want to know that "most things like X are Y". We're trying to prove that "this building is probably not-dwelling". So we would want to know that "most things like this building were not-dwellings". If we knew, for example, that "most buildings made from more than one type of stone were not-dwellings", then we would have a solid argument. The evidence here allows for a Most + Most inference. Since most buildings from this time/place were made of only one type of stone and most buildings from this time/place were dwellings, we can infer that "AT LEAST ONE dwelling was made from only one type of stone". But we're missing any ammunition that would allow us to go from "this building is multi-stoned" to "this building is PROBALY not a dwelling."

Correct Answer:
B

Answer Choice Analysis:
(A) This does nothing. If anything, it opens the door for the idea that dwellings could have sometimes been make only partially of limestone, just like this building.

(B) This is the best choice we've got. This would be better if it were backwards. We would love to hear that "most buildings that involved non-local stones (as did this building) were not dwellings". But since this is Strengthen, not Sufficient Assumption, we can live with picking an answer that adds plausibility, albeit imperfectly.

(C) This answer choice makes the building in question seem like an oddball in terms of the other stones it used beyond the local limestone. But making this building seem like an oddball doesn't help us evaluate the dwelling vs. not dwelling issue of the conclusion.

(D) This might come closer to a weaken answer. If most buildings at the site were dwelling, then ANY building at the site, without any addiitonal information, would probably be a dwelling.

(E) This is like (C), in that it just makes the building in question seem like an oddball, but doesn't help us evaluate whether the building was a dwelling or not.

Takeaway/Pattern: This was a tough one, because the test is definitely triggering our understanding of "most + most" inferences, as well as our knowledge that in order to prove "This A is probably B" we need to know "Most A's are B". The correct answer, "Most B's are A" is not the correct idea we need to establish the conclusion (it's backwards from being THAT useful), it still does add some plausibility to this argument, so it still counts as providing more support than any other answer.

#officialexplanation

[melnauni]

I chose the correct answer B primarily by process of elimination. But I have a hard time understanding how it actually strengthens the logic. Here is how I understand the argument in simple terms:

Premise#1: Our building is composed not only of limestone.

Premise# 2: Most of the building from the same time as our building are composed only of limestone. (most buildings-->limestone only)

Premise # 3: Most of the building that are composed only of limestone are dwelling. (most limestone only --> dwellings).

Conclusion: Our building probably not a dwelling.

I was thinking that in order to conclude, from the premise that most limestone buildings are dwellings, that our building is not a dwelling we must assume that our building must be composed not only of lime stone. This assumption, in my opinion, could be stated in such terms: Most buildings composed not only of limestone are not dwellings). The correct answer B, states this in a reverse form: most not dwellings are composed not only of limestone. But how do sentences with most could be reversed like that? I think we can make any sort of probability conclusion only if we follow this --> direction of an arrow. For example, imagine an argument: Most students like their professors. Therefore, Ann is probably not a student. Will the statement "Most non-students don't like their professors" strengthen the conclusion here? Conversely, an inference "If Ann is a student, she probably likes her professor" would seem valid. In other words, B seems to go against the arrow in a "most" sentence, which doesn't seem right to me. Could you explain please? Also, what does the second word "most" refer to, i.e. Does it refer to most of limestone-only buildings or to most of the buildings at the site in general ( which would mean only that some dwellings are composed only of limestone).

Thanks a lot!

[ManhattanPrepLSAT1]

I was thinking that in order to conclude, from the premise that most limestone buildings are dwellings

We don't know this is true from the stimulus, nor by adding answer choice (B), which only makes the conclusion more likely to be true. We know that most buildings were made only of limestone. We also know that most buildings were human dwellings. From this we could infer that some limestone buildings were human dwellings, but not that most limestone buildings were human dwellings.

I don't see a good way to use formal logic on this question as it's more a play with a complicated set of overlapping percentages. One possible way to see the overlapping percentages is with a Venn Diagram.



The greater the proportion of non-dwellings that are made of material other than just limestone, the greater the percentage of dwellings will be made of just limestone, since we know that most buildings are made only of limestone. This will in turn increase the ratio of those buildings made of more than just limestone that are non-dwellings and so support the conclusion.

Hope that helps!

[wang0822]

Please double check your chart, mshermn.

There are two portions of "more than limestone", with one portion larger in "dwelling". So how to draw the conclusion that if something is made more than limestone, it is probably not a dwelling. I would argue it is more likely a dwelling than a non-dwelling.

Honestly, I think this question is flawed. But we can get B from POE. Because:
(1) we are asked to find the most strengthen choice;
(2) there is no way for ACDE to strengthen, since they are either out of scope or weaken;
(3) (B) can weaken as shown in your chart; but can also strengthen by assigning the "more than limestone" in "dwelling" a much smaller percentage of the entire "dwelling".

[ManhattanPrepLSAT1]

There are two portions of "more than limestone", with one portion larger in "dwelling". So how to draw the conclusion that if something is made more than limestone, it is probably not a dwelling. I would argue it is more likely a dwelling than a non-dwelling.

You're absolutely right, we cannot draw the conclusion that the building is probably not a dwelling. But answer choice (B) does make it more likely that the building is probably not a dwelling.

The problem is that most buildings are dwellings. Just as an example let's say dwellings make up 60% of buildings and those that are not make up 40%. Given only this claim the chances are that the building in question would be a dwelling.

But let's also consider that most buildings are made only of limestone, though our particular building is not. Well we don't know how to distribute the buildings made only of limestone into the two groups. Answer choice (B) helps us with that by suggesting that most of the buildings that are not dwellings are made of materials other than just limestone. That increases the percentage of dwellings that will be made only of limestone. The larger that proportion is the larger the chance will be that the building made only of limestone will not be a dwelling.

So while answer choice (B) will not allow you to draw the conclusion, it will support it.

Hope that helps!

[rwayersiii]

This question is a bit confusing to me. It seems to me that the author believes that if limestone is not the only stone component, then most likely the building is not a dwelling. Which the author clearly does not support in the stimulus. B seems to be a reverse of that statement.

But it also seems that E strengthens the argument. We are told that most of the buildings on the site are dwellings. What E is doing is giving us information that shows how the building being studied is different from the other buildings at the site, most of which are dwellings. So if our building is different from most of those other buildings which are dwellings, then maybe our building is not a dwelling. It doesn't conclusively prove that it is not a dwelling, but the conclusion is not an absolute statement so we don't need our answer to conclusively prove it.

[gplaya123]

Here is my 2cent.
Someone please check my work.

I think the most important thing to recognize is the assumption that the author makes in the end: by saying that whatever they are studying isn't a dwelling, they are implying that they are not made up limestone.

However if most of the dwellings were made up of limestone and whatever they studying isn't made up of limestone like they say in the argument, then it strengthens the argument.

[sch6les]

You need to understand the following in order to get this question:

If all A => B
- I can infer some B => A
If most A => B
- I can infer some B => A
If some A => B
- I can infer some B => A

You should also understand that:
>50% chance of happening = likely/probably
<50% chance of happening = unlikely/probably not

Now, the conclusion in the stimulus is:
It is probable that the ~limestone-only building we are studying is ~dwelling.

In formal notation:
Most ~limestone-only building => ~dwelling

Therefore, I can infer:
Some ~dwelling => ~limestone-only building

(B) encapsulates this, by saying:
Most ~dwelling => ~limestone-only building

Therefore, (B) strengthens the argument.

______________________

FYI, the premises don't come close to justifying the conclusion. They are:

(1) Most building => limestone-only
(2) Most building => dwelling

The only thing you can infer from this is:
- some limestone-only => dwelling
- some dwelling => limestone-only

[ManhattanPrepLSAT1]

You need to understand the following in order to get this question:

If all A => B
- I can infer some B => A
If most A => B
- I can infer some B => A
If some A => B
- I can infer some B => A

You should also understand that:
>50% chance of happening = likely/probably
<50% chance of happening = unlikely/probably not

Now, the conclusion in the stimulus is:
It is probable that the ~limestone-only building we are studying is ~dwelling.

In formal notation:
Most ~limestone-only building => ~dwelling

Therefore, I can infer:
Some ~dwelling => ~limestone-only building

(B) encapsulates this, by saying:
Most ~dwelling => ~limestone-only building

Therefore, (B) strengthens the argument.

______________________

FYI, the premises don't come close to justifying the conclusion. They are:

(1) Most building => limestone-only
(2) Most building => dwelling

The only thing you can infer from this is:
- some limestone-only => dwelling
- some dwelling => limestone-only

Those are some interesting points sch6les! I think I would disagree with your point that the way answer choice (B) strengthens the argument is by strengthening an inference of the conclusion. While the inference you drew is correct, supporting the inference, will not in turn support the argument's conclusion.

Also, I would disagree that the premises aren't worth using in supporting the argument. I think that the premises are actually quite important in order for answer choice (B) to strengthen the argument's conclusion.

[ptewarie]

Don't make it too confusing guys! This is just a simple assumption question.

Author says:
The building they found is not only made up of Limestone so its probably not a dwelling.

That just means that his assumption is that buildings that were not a dwelling are not only made up of limestone, which is what Answer choice B states.

So:

P1:
The building they found is not only made up of Limestone

P2: Most dwellings only use limestone

Strengthener(choice B)
+ Other buildings besides dwellings use other material besides limestone

Conclusion:
So the building we found is not a dwelling

Bingo!

Again, one would think, sure but how does this strengthen the argument? Well it does. Remember, strengtheners make the conclusion more likely by STRENGTHENING THE ASSUMPTION.


Think of it like this( simplified version):

The object we found on the playground was shiny and bright. Soccer balls, however, are never shiny and dark , so it's not a soccer ball.

Assumption: There are other objects besides soccer ball that can be shiny and bright.

[amil91]

This question is a bit confusing to me. It seems to me that the author believes that if limestone is not the only stone component, then most likely the building is not a dwelling. Which the author clearly does not support in the stimulus. B seems to be a reverse of that statement.

But it also seems that E strengthens the argument. We are told that most of the buildings on the site are dwellings. What E is doing is giving us information that shows how the building being studied is different from the other buildings at the site, most of which are dwellings. So if our building is different from most of those other buildings which are dwellings, then maybe our building is not a dwelling. It doesn't conclusively prove that it is not a dwelling, but the conclusion is not an absolute statement so we don't need our answer to conclusively prove it.

I think E is tempting in the real world, but for the LSAT it doesn't actually address the gap in the argument. It does not connect the material of the build, in this case the fact that it has things other than limestone (quartz), to ~dwelling. So what if quartz has never been discovered on the site in any other building. That doesn't really give any support for that building not being a dwelling. Sure it is different, but maybe it was for the head of the village?

Don't make it too confusing guys! This is just a simple assumption question.

Author says:
The building they found is not only made up of Limestone so its probably not a dwelling.

That just means that his assumption is that buildings that were not a dwelling are not only made up of limestone, which is what Answer choice B states.

So:

P1:
The building they found is not only made up of Limestone

P2: Most dwellings only use limestone

Strengthener(choice B)
+ Other buildings besides dwellings use other material besides limestone

Conclusion:
So the building we found is not a dwelling

Bingo!

Again, one would think, sure but how does this strengthen the argument? Well it does. Remember, strengtheners make the conclusion more likely by STRENGTHENING THE ASSUMPTION.


Think of it like this( simplified version):

The object we found on the playground was shiny and bright. Soccer balls, however, are never shiny and dark , so it's not a soccer ball.

Assumption: There are other objects besides soccer ball that can be shiny and bright.

I disagree with the bolded statement. The stim says most buildings are made of only limestone and most buildings are human dwellings, that does not mean most buildings are both limestone only and human dwellings, simply that some buildings are both human dwellings and made of only limestone.

I think the easiest way to answer this is quick POE:
A - Is kind of a premise booster and doesn't connect -only limestone to -dwelling.
C - Is irrelevant for similar reason to A. It does not address the gap. And who cares of most of the buildings that were not only limestone also did not have quartz and granite.
D - Is a restatement of a premise.
E - Irrelevant, it doesn't address the gap in the argument.

[ManhattanPrepLSAT1]

I disagree with the bolded statement. The stim says most buildings are made of only limestone and most buildings are human dwellings, that does not mean most buildings are both limestone only and human dwellings, simply that some buildings are both human dwellings and made of only limestone.

Good point amil91, that's absolutely right!

[Mab6q]

Wow, I must say that there are about 10 different explanations for this question and none of them seem to make any sense. There certainly is alot of false diagramming for this question here. I'm going to give it my best shot but I would appreciate it if some of Manhattan folks would give a clear understanding and breakdown of this problem. Here's how I approached it.

Conclusion: the building we are studying probably was not a dwelling.

Support 1: Buildings from the site --M--> only limestone
Support 2: Buildings from the site --M--> human dwellings
Support 3: This stone building has limestone, quartz and granite, and only the limestone occurs naturally in the area.

This is a terrible argument. The author is assuming that somehow we know which buildings are not dwellings based on most of the buildings being human dwellings and most being made only of limestone, but there's no way we can.

At best, we know that one building that was made only of limestine was a human dwelling, which could mean the other 49 % that were not only limestone were human dwellings.

The Answer Choices

A. this is useless, as it does not rule out the possibility that our building was included in this list.

B. ~Not Dwellings --m--> ~only limestone (i think it's easier to write it out as only limestone for conditionals sake)
Although I suppose this does help in the least bit by telling us that most ~non dwellings have a quality (~only limestone) that our building also has, I must say this is the weakest strengthener I've ever seen and is very unusual by LSAT standards.

C. is irrelevant because it tells us nothing about human dwellings.

D. this is pretty much a premise booster, with the exception that is extends one of our premises to all buildings and not just those from that time period.

E. irrelevant.

I really hope we get some more discussion on this question because it's really giving me a hard time. How do we approach such problems. How often does the LSAT use a question where there really is no good answer just 4 terribly wrong ones. Thanks!

[ying_yingjj]

I think Matt Sherman's chart does not make sense at all. Not only does not make sense, but also misleading. I suggest to take that chart down.

As a data analyst, I deal with data and charts everyday, let me try to explain like this:

Say we have 100 buildings found at that site: most are limestone only- say 65 limestone only buildings, they include buildings for dwelling and non-dwelling; 35 are other stones.

Same 100 buildings, lets count how many buildings are for dwellings, and non-dwellings: it can be a coincident, that exactly limestone only buildings happen to be for dwelling, and the remaining 35 are for non-dwelling.

So the non-dwelling 35 buildings are all made from other stones (matches exactly the 35 buildings made from other stones).

if all of the now-dwelling buildings (35) ---> made from other stones
and we found an ancient stone building from the site was composed of three kinds of stones (other stones)

Does it increase (strengthen) the possibility, that at least one (this building we found at the cite) building with other stones is non-dwelling?

Absolutely!

And, most means (51%-100%), so, (B) can be read as, All of the buildings at the site that were not dwellings were made, at least in part, from types of stone that do not occur naturally in the area. It definitely strengthens.

[LsatCrusher822]

I think what Ying is trying to say here is that the author is indeed assuming that the "most of the buildings at the site from the time period had limestone as their only sone component" is the same as "most were human dwellings" (or at least there is a significant overlap between these two group). That is the only way that we can logically get to the conclusion that the building (having quartz, granite and limestone) is NOT a dwelling.

We have to assume that the other "some" not considered by the two premises also have a significant overlap. Somebody please correct me if I am wrong, but we are able to take the logical opposite of "most" statement by adding a NOT and changing the most to some

Thus we can get the flip side of the "most" statements as:
1) Some of the building did NOT have limestone as their only stone component, and
2) Some of the buildings were NOT human dwellings

We also then need to assume there is a major overlaps, if not the two some statement being the same. This is what answer choice B does for us! Answer B would also be correct is "most" was substituted by "all"

[JulianG99]

You need to understand the following in order to get this question:

If all A => B
- I can infer some B => A
If most A => B
- I can infer some B => A
If some A => B
- I can infer some B => A

You should also understand that:
>50% chance of happening = likely/probably
<50% chance of happening = unlikely/probably not

Now, the conclusion in the stimulus is:
It is probable that the ~limestone-only building we are studying is ~dwelling.

In formal notation:
Most ~limestone-only building => ~dwelling

Therefore, I can infer:
Some ~dwelling => ~limestone-only building

(B) encapsulates this, by saying:
Most ~dwelling => ~limestone-only building

Therefore, (B) strengthens the argument.

______________________

FYI, the premises don't come close to justifying the conclusion. They are:

(1) Most building => limestone-only
(2) Most building => dwelling

The only thing you can infer from this is:
- some limestone-only => dwelling
- some dwelling => limestone-only

Yea....... I would definitely not follow this way of solving this question. Its way too much.

[SJK493]

[b][size=100]Takeaway/Pattern: This was a tough one, because the test is definitely triggering our understanding of "most + most" inferences, as well as our knowledge that in order to prove "This A is probably B" we need to know "Most A's are B". The correct answer, "Most B's are A" is not the correct idea we need to establish the conclusion (it's backwards from being THAT useful), it still does add some plausibility to this argument, so it still counts as providing more support than any other answer.

#officialexplanation

I know that this is a Strengthen question, but what kind of answer would establish the conclusion? (